/* * Copyright (c) 1997, 2002, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. * */ // The classes in this file provide a simple framework for the // management of little pieces of machine code - or stubs - // created on the fly and frequently discarded. In this frame- // work stubs are stored in a queue. // Stub serves as abstract base class. A concrete stub // implementation is a subclass of Stub, implementing // all (non-virtual!) functions required sketched out // in the Stub class. // // A concrete stub layout may look like this (both data // and code sections could be empty as well): // // ________ // stub -->| | <--+ // | data | | // |________| | // code_begin -->| | | // | | | // | code | | size // | | | // |________| | // code_end -->| | | // | data | | // |________| | // <--+ class Stub VALUE_OBJ_CLASS_SPEC { public: // Initialization/finalization void initialize(int size) { ShouldNotCallThis(); } // called to initialize/specify the stub's size void finalize() { ShouldNotCallThis(); } // called before the stub is deallocated // General info/converters int size() const { ShouldNotCallThis(); return 0; } // must return the size provided by initialize static int code_size_to_size(int code_size) { ShouldNotCallThis(); return 0; } // computes the size given the code size // Code info address code_begin() const { ShouldNotCallThis(); return NULL; } // points to the first byte of the code address code_end() const { ShouldNotCallThis(); return NULL; } // points to the first byte after the code // Debugging void verify() { ShouldNotCallThis(); } // verifies the Stub void print() { ShouldNotCallThis(); } // prints some information about the stub }; // A stub interface defines the interface between a stub queue // and the stubs it queues. In order to avoid a vtable and // (and thus the extra word) in each stub, a concrete stub // interface object is created and associated with a stub // buffer which in turn uses the stub interface to interact // with its stubs. // // StubInterface serves as an abstract base class. A concrete // stub interface implementation is a subclass of StubInterface, // forwarding its virtual function calls to non-virtual calls // of the concrete stub (see also macro below). There's exactly // one stub interface instance required per stub queue. class StubInterface: public CHeapObj { public: // Initialization/finalization virtual void initialize(Stub* self, int size) = 0; // called after creation (called twice if allocated via (request, commit)) virtual void finalize(Stub* self) = 0; // called before deallocation // General info/converters virtual int size(Stub* self) const = 0; // the total size of the stub in bytes (must be a multiple of CodeEntryAlignment) virtual int code_size_to_size(int code_size) const = 0; // computes the total stub size in bytes given the code size in bytes // Code info virtual address code_begin(Stub* self) const = 0; // points to the first code byte virtual address code_end(Stub* self) const = 0; // points to the first byte after the code // Debugging virtual void verify(Stub* self) = 0; // verifies the stub virtual void print(Stub* self) = 0; // prints information about the stub }; // DEF_STUB_INTERFACE is used to create a concrete stub interface // class, forwarding stub interface calls to the corresponding // stub calls. #define DEF_STUB_INTERFACE(stub) \ class stub##Interface: public StubInterface { \ private: \ static stub* cast(Stub* self) { return (stub*)self; } \ \ public: \ /* Initialization/finalization */ \ virtual void initialize(Stub* self, int size) { cast(self)->initialize(size); } \ virtual void finalize(Stub* self) { cast(self)->finalize(); } \ \ /* General info */ \ virtual int size(Stub* self) const { return cast(self)->size(); } \ virtual int code_size_to_size(int code_size) const { return stub::code_size_to_size(code_size); } \ \ /* Code info */ \ virtual address code_begin(Stub* self) const { return cast(self)->code_begin(); } \ virtual address code_end(Stub* self) const { return cast(self)->code_end(); } \ \ /* Debugging */ \ virtual void verify(Stub* self) { cast(self)->verify(); } \ virtual void print(Stub* self) { cast(self)->print(); } \ }; // A StubQueue maintains a queue of stubs. // Note: All sizes (spaces) are given in bytes. class StubQueue: public CHeapObj { friend class VMStructs; private: StubInterface* _stub_interface; // the interface prototype address _stub_buffer; // where all stubs are stored int _buffer_size; // the buffer size in bytes int _buffer_limit; // the (byte) index of the actual buffer limit (_buffer_limit <= _buffer_size) int _queue_begin; // the (byte) index of the first queue entry (word-aligned) int _queue_end; // the (byte) index of the first entry after the queue (word-aligned) int _number_of_stubs; // the number of buffered stubs Mutex* const _mutex; // the lock used for a (request, commit) transaction void check_index(int i) const { assert(0 <= i && i < _buffer_limit && i % CodeEntryAlignment == 0, "illegal index"); } bool is_contiguous() const { return _queue_begin <= _queue_end; } int index_of(Stub* s) const { int i = (address)s - _stub_buffer; check_index(i); return i; } Stub* stub_at(int i) const { check_index(i); return (Stub*)(_stub_buffer + i); } Stub* current_stub() const { return stub_at(_queue_end); } // Stub functionality accessed via interface void stub_initialize(Stub* s, int size) { assert(size % CodeEntryAlignment == 0, "size not aligned"); _stub_interface->initialize(s, size); } void stub_finalize(Stub* s) { _stub_interface->finalize(s); } int stub_size(Stub* s) const { return _stub_interface->size(s); } bool stub_contains(Stub* s, address pc) const { return _stub_interface->code_begin(s) <= pc && pc < _stub_interface->code_end(s); } int stub_code_size_to_size(int code_size) const { return _stub_interface->code_size_to_size(code_size); } void stub_verify(Stub* s) { _stub_interface->verify(s); } void stub_print(Stub* s) { _stub_interface->print(s); } static void register_queue(StubQueue*); public: StubQueue(StubInterface* stub_interface, int buffer_size, Mutex* lock, const char* name); ~StubQueue(); // General queue info bool is_empty() const { return _queue_begin == _queue_end; } int total_space() const { return _buffer_size - 1; } int available_space() const { int d = _queue_begin - _queue_end - 1; return d < 0 ? d + _buffer_size : d; } int used_space() const { return total_space() - available_space(); } int number_of_stubs() const { return _number_of_stubs; } bool contains(address pc) const { return _stub_buffer <= pc && pc < _stub_buffer + _buffer_limit; } Stub* stub_containing(address pc) const; address code_start() const { return _stub_buffer; } address code_end() const { return _stub_buffer + _buffer_limit; } // Stub allocation (atomic transactions) Stub* request_committed(int code_size); // request a stub that provides exactly code_size space for code Stub* request(int requested_code_size); // request a stub with a (maximum) code space - locks the queue void commit (int committed_code_size); // commit the previously requested stub - unlocks the queue // Stub deallocation void remove_first(); // remove the first stub in the queue void remove_first(int n); // remove the first n stubs in the queue void remove_all(); // remove all stubs in the queue // Iteration static void queues_do(void f(StubQueue* s)); // call f with each StubQueue void stubs_do(void f(Stub* s)); // call f with all stubs Stub* first() const { return number_of_stubs() > 0 ? stub_at(_queue_begin) : NULL; } Stub* next(Stub* s) const { int i = index_of(s) + stub_size(s); if (i == _buffer_limit) i = 0; return (i == _queue_end) ? NULL : stub_at(i); } address stub_code_begin(Stub* s) const { return _stub_interface->code_begin(s); } address stub_code_end(Stub* s) const { return _stub_interface->code_end(s); } // Debugging/printing void verify(); // verifies the stub queue void print(); // prints information about the stub queue };